Technical interview questions and answers are essential for J2SE Interviews because core Java concepts form the foundation of all Java-based development. Companies test your knowledge of OOP principles, exceptions, packages, JVM architecture, threading, collections, and file handling. These topics commonly appear in placement drives and technical interviews conducted by TCS, Infosys, Wipro, Cognizant, and Capgemini. Understanding J2SE concepts helps freshers and job seekers prepare for both Java developer roles and advanced J2EE/Java EE interviews. This guide features the most commonly asked J2SE interview questions with answers explained in simple language. Preparing these questions will strengthen your Java basics and improve your performance in coding tests and technical rounds.
Java programmers should advance their enterprise skills by studying J2EE frameworks and mastering EJB components for distributed applications
Showing 7 of 237 questions
231. What is volatile ?
A Java keyword used in variable declarations that specifies that the variable is modified asynchronously by concurrently running threads.
232. What is Web server ?
Software that provides services to access the Internet, an intranet, or an extranet. A Web server hosts Web sites, provides support for HTTP and other protocols, and executes server-side programs (such as CGI scripts or servlets) that perform certain functions
233. What is while ?
A Java keyword used to declare a loop that iterates a block of statements. The loop's exit condition is specified as part of the while statement.
234. What is world readable files ?
Files on a file system that can be viewed (read) by any user. For example: files residing on Web servers can only be viewed by Internet users if their permissions have been set to world readable.
235. What is wrapper ?
An object that encapsulates and delegates to another object to alter its interface or behavior in some way.
236. What is XML ?
Extensible Markup Language. A markup language that allows you to define the tags (markup) needed to identify the data and text in XML documents.
237. What is constructor ?
A pseudo-method that creates an object. In the Java programming language, constructors are instance methods with the same name as their class. Constructors are invoked using the new keyword.